Hydraulic power pack unit



July 6, 1948. a. N. ASHTON l HYDRAULIC POWER PACK UNIT 2 Sheets-Sheet 1 y Filed May 20, 1944 MrraH/sz'ys' .Fuy 6, 1948. l B, N, AgsH'roN l 2,444,550

HYDRAULIC PQwER PACK UNIT Fled May 20, 11944 y 2 Sheets-Sheet 2 if, w

Lw Trax/V516 Patented July6, 1948 UNrrED STATE-.s PATENT fOmCEV.

HYDRAULIC POWER PACK UNIT Benjamin N. Ashton, Kingston, N. Y., asslgnor to Electrol Incorporated, Kingston, N. Y., a corporation of Delaware Application May 2o, 1944, serial 101536,492

This invention relates to hydraulic power pack units and relates particularly to liquid pump and accumulator units for use in supplying liquid under pressure to hydraulic systems.

The hydraulic systems now commonly in use for actuating the landing gear, wing flaps, cowl aps and the like of airplanes are complex constructions requiring large amounts of conduit for delivering the liquid under pressure to the hydraulic cylinders or motors that are used for actuating the flaps and landing gear. Usually, the pressure liquid is supplied by a pimip connected directly to the airplane engineand this pump is connected in turn by a long conduit to an accumulator for receiving the liquid under pressure and maintaining a head of liquid in the system; The conduits lead back from the accumulator, which is usually remote from `the pump. to the various selector valves in or adjacent to the cockpit and thence to the variousv hydraulic motors or cylinders which are likewise disposed at points, remote from the cockpit of the airplane.-

A great deal of weight would be saved, installation costs decreased, and danger of damage to the system by gun tire or other causes would be reduced if the pump, accumulator and other operating elements of the system were combined in a relatively compact unit. l

Accordingly, an object of the present invention is to provide a small and compact power unit including a pump and an accumulator for supplying liquid under pressure within a predeter-- have provided an hydraulic power supply unit including an accumulator in which is telescopically received a :pump for supplying liquid under pressure to the accumulator and also to the conduits for actuating the various hydraulicv motors ,ofl an airplane.

More particularly, I have utilized an accumulator of the type disclosed in my Patent No. 2,365,-

994, December 26, 1 944, in conjunctionwith a piston type pump oi' the type disclosed in my Patent No. 2,405,006, July 3G, 1946, these elements being Figure 2 is a view in cross-section taken on line 2--2 of Figure 1; and

Figure 3 is a view in cross-section taken on line 3-3 of Figure 2.

The form of power unit chosen to illustrate the present invention includes an vaccumulator AII) of the type disclosed in my Patent No. 2,365,994.

which includes a generally cylindrical casing II having one end closed by a plate I2 which may be formed integrally therewith or welded to the end y of the casing I'I, as illustrated. Within the casing II is disposed a cylindrical lsleeve I3 havingl an enlarged externally threaded end portion I4 that is screwed into the end of the casing 'II and secured thereto. The end of the sleeve I3 is provided with a disc-like closure I5 having a centrally located port IB therein and is provided with a threaded flange Il that is'screwed into the left-hand end of the sleeve I3. Adjacent portions of the sleeve I3 and the closure member I5 are provided with opposed grooves forming a cavity I8 forreceiving a, rubbery sealingring I9. The-end closure member I5 is also provided with a raised portion 20 having a. substantially ilat surface 2l forming the seat for a valve member later to`be described. The fiat surface is provided with an annular groove 22 encircling the port I6 for reception of a rubbery ring 23.

Betweenthe sleeve I3 and the casing II is disposed a flexible corrugated metallic bellows 24 v having a cylindrical end portion 25 and a flared portion 2 6. The cylindrical portion 25 and the ared portion 26 are clamped between complementally shaped surface Iportions 21 on the sleeve member I3 and a complementally shape'dfportion 28 on a ring member 29 that is interposed between a portion of the sleeve I3 and the casing I I.

against the ring member 38, the right-hand end of the bellows is rmly retained.

In order to prevent leakage between the sleeve I3, the ring 29 and the casing II, the sleeve I3 may be provided with a peripheral groove 32 for receiving a sealing ring 33 and the ring may be provided with an internal groove 34 and an external groove 35 for receiving sealing rings 36 and 31, respectively.

The left-hand end of the bellows 24' is provided with a rigid disc-like end plate 38 which upon contraction of the bellows 24 engages the sealing ring 23 and the valve seat '2l to trap liquid between the bellows and the sleeve I3 and thereby prevent collapse of the bellows 24 by air pressure between the bellows and the casing I I .A

Air may be introduced into the casing II through an air check valve 39.

The internal sleeve I3 receives telescopically a piston type of pump 40 of the type disclosed generally in my Patent No. 2,405,005. The pump 40 is provided with a generally cylindrical body portion 4I (Figure 2) having three enlargements 42, 43 and 44 extending longitudinally thereof. The enlargement 42 is bored axially to form an intake conduit 45 and is provided with an intersecting laterally extending bore 46 which is internally threaded to receive a fitting on a conduit (not shown). Theouter end of the lbore v46 may be. closed by a suitable threaded plug 41 sealed thereto by a sealing ring 48.

The bore 4'4 is similarly provided with a longitudinally extending bore 49 and an intersecting lateral bore 59 which is internally threaded to receive a coupling on the end of a discharge conduit (not shown). The cylindrical pump body 4I is retained in position by means of a cylindrical ange 52 on an annular base plate 53 that is secured to the pump body and to the sleeve I3 of the accumulator by means of a plurality of bolts 54 disposed around its periphery.

The cylinder block I is provided with a plurality of cylinders 55 extending parallel to the axis of the block and arranged in a circle around the axis of the block. The block is provided with a peripheral groove 55 which intersects the cylinders 55 at a point about midway of their length A and communicates through an opening 51 with the inlet bore 45 so that liquid can be drawn into the cylinders 55 by the cylindrical pistons 58 that are slidably received in the cylinders 55. c

At the inner end of each cylinder 55 is mounted a check valve 59 which includes an annular seat sleeve 60 that is threaded into the end of the cylinder and sealedthereto by means of a sealing ring 5I. The end face 62 of the sleeve 60 is somewhat enlarged and is provided with an annular groove 63 for receiving a sealing ring` B4 formed of rubbery material. The seat cooperates with a valve plug in the form of a plate member 55 having reversely turned ilanges or lugs 66 thereon which retain and guide a coil spring 61 that bears against the end closure 68 of the cylindrical body portion 4i.

As the pistons 58 are retracted in the cylinders 55, a reduced pressure is created that draws liquid into the cylinder through the port 51 and the groove 55. Upon forward movement of the piston, the liquid is forced through the valve seat sleeve 60, thereby displacing the valve plug 65 and forcing the liquid into a generally annular chamber 59 between the end member 68 of the valve housing and the cylinder block 5I. This chamber 59 communicates directly with the discharge bore 49 so that the liquid pumped can be 4 discharged directly to the hydraulic system connected with the bores 49 and 50.

The end member 68 of the pump housing 4I is provided with an annularflange 18 which nts within a cylindrical recess 1I extending axially of the cylinder block-50. The cylinder block is provided with an annular projecting ilange 12 which maintains the cylinder block 5I in proper spaced relationship to the end 68 of the casing.

The flange 10 terminates short .oi' the bottom of the recess 1I, thereby leaving space for a piston I3 which has a piston rod 14 slidably received in another inner concentric ange fixed to the end 68 of the casing. A spring 15a is received in the annular space between the anges 1I) and 15 and bears against the piston 13, urging it to the right. The piston is provided with a peripheral groove 18 for receiving a seaiing ring 11 for cooperation with the wall of the -cavity 1 I. The piston rod 14 is also provided with a sealing ring 18 cooperating with the inner surface of the flange 15 and is lfurther provided with a bore 19 that opens to the recess 1I at the right-hand side of the piston 13. Another piston rod is secured tothe right-hand side of the piston 13 and extends through a bore 8l in the cylinder block 50. The piston rod 80 may be sealed to the bore by means of a sealing ring 82.

A ball member 83 is secured to the right-hand end of the piston rod 80 and acts as a support for a wobble plate 84 for driving the pistons. wobble plate 84 may consist of atwo-element construction. one of which is a anged disc 85 having a semi-spherical inner surface 86 and in- .ternal threads 81 for receiving an externally threaded collar 88 having a semi-spherical inner surface 89. The wobble plate 84 is provided with radially extending pins 90 Ihaving ball-like outer ends 9| that are received in transverse bores 92 in the reduced end portions 93 ofthe pistons 58. The wobble plate 84 is driven by means of a driveshaft 94 that may be connected to a motor or an airplane engineand is rotatably mounted in an anti-friction bearing 95 that is secured in the annular plate 53. The shaft 94 is provided with a disc-like counter-balancing member 98 having an inclined annular flange 91 disposed in a cut-away portion 98 of thecopnter-balance member 96. The ilange 91 is disposed eccentrically to the axis of the shaft 94 and is so inclined that its axis intersects the center of the ball 83 in the position shown in Figure 1. The

`ilange`91 carries a roller thrust bearing 99, the

outer race of which bears against the flange on the wobble plate 84 and upon rotation causes a nutating movement of the wobble plate 84 with consequent successive reciprocation of the pistons.. The bearing 99 may .be retained on the ilange 91 by means of a ilanged, cup-shaped member M0 secured within thefiange 91 and overlying the inner race of the bearing 99.

As described above, the pump 40 delivers liquid through the discharge part 50. The chamber 69 in which the pressure iluid is received from the cylinders is so connected to the interior of the sleeve I3 and the interior of the bellows 24 ing device includes a transverse bore |02 the left-hand end of the pump housing which communicates with the chamber 69by means of the passageways |03 and |04.v Adjacent the inner end of the bore |02 is mounted an annular valve seat |05 having a central passage |08 defining a seat for the ball valve |01.

Encircling the mid-portion of the ball is an annular -spacer ring |08 which is provided with a transverse port |09 communicating with a peripheral groove I I that communicates through a passage with the interior of the sleeve 15. Supported on the spacer ring |08 is a sleeve ||2 having a seat ||8 therein for the ball |01, the seat |3 being somewhat larger in diameter than the seat in the lower member |05. The member and the sleeve ||2 have their peripheries sealed to the walls of the bore |02 by suitable sealing rings.

The elements |05. |08 and ||2 are maintained in ilxed relationship by. means of a sleeve ||4 threaded into the bore |02 and further engaged by an outer lock sleeve H5. The outer lock lsleeve ||5 is provided with a ring seal ||6 and a central aperture for receiving a plunger ||1 that bears against the ball |01 and forces it toward the ring |05. 'Ihe upper end of a spring ||8 encircling the rod ||1 bears against a washer |'|9 that engages a Sealing ring |20 and prevents leakage around the plunger. The opposite end of the spring ||8 engages a ange |2| on the rod.

The sleeve |4 is provided with a port |22 which communicates with another port |28 communicating with the intake side oi the cylinders at the groove 56.

The above-defined unloader construction operates in the following manner. As the pistons oi.' the pump deliver iluid into the chamber 09 and the pressure increases, the pressure on the ball valve |01 increases correspondingly. At a predetermined maximiim pressure, determined by the strength of the spring H8 and the diameter of the port |06, the ball isdlsplaced upwardly.

.thereby permitting liquid to ilow through the passages |03, |04 and the port 06, the passages |09, I, through the bore 19 in the piston rod 14 to the right-hand side of the piston 13. The pressure of the liquid on the piston displaces it ,to

the left, thereby carrying with it the wobble plate 84 and displacing all of the pistons 58 to the left. This disconnects the wobble plate 84 from the driveshaft 94 and pumping is discontinued until operation of an element connected with the pump or leakage in the system reduces the pressure to a predetermined minimum. The accumlulator i0. of course, tends to maintain the pressure constant over extended periods of time and supplies additional fluid when the pump is not working.

The pressure at which the pump again goes into operation is .determined by the area of the ball valve |01 in contact with seat ||8. Inasmuch as the seat ||3 is larger than the port |06, the pressure must drop below the maximum pressure before the spring ||8 can displace thefball downwardly. When this occurs. the spring a urges the piston 13 to the right and the liquid flows through the bore 19 in the piston rod 14, the passage the passage |09 through the now open seat |`|3 and out through the ports |22 and |23 to the intake side of the pump. This movement of the piston to the right re-engages the wobble plate 64with the drive mechanism andsets the pump into operation.

In addition to the construction described above, the system may be provided witha relief valve construction,best shown in Figure 3. The relief valve is mounted in a bore |24 extending axially of the enlargement 43 and has lts outer end sealed by means of a suitable sealing plug |25. The bore |24 communicates with a trans-A verse bore |26 which is connected to a suitable relief conduit, not shown. -The inner end of the p. closely adjacent to the selector valves of the hy- 't draulic system which then need only be connectedk i0 bore |24 communicates with thech'amber 69. The bore |24 is provided with a shoulder |21 against which bears a ring valve seat |28 sealed to the bore wall by means oi a sealing ring |29. A valve plug cooperates with the seat ring l|28 and has a conical valve element |8|I thereon and a cylindrical body portion |82 for guiding the valve in a sleeve |33 threaded into the bore |24.

The valve |80 is urged toward the seat |28 by means of a compression spring |84 that engages a sleeve |85' threaded into the outer end of the sleeve |88. The valve |30 may also be provided with a stem |86 for maintaining the spring cen allow the liquid to be discharged through suitable passages |31 in the cylindrical portion |32.

The above-described construction can be made of any size suitable for the requirements of the hydraulic system and because ofits telescopic relationship can be made much more compact than prior pump 'and accumulator devices.

The device has many advantages, including ease of installation, compactness and reduction of the number and length of .conduits in the systerm Thus, the whole unit may be positioned by conduits of suitable length to the hydraulic motors for actuating the elements o'f an aircraft.

It will be understood that the device is susceptible to considerable modification in the details of the accumulator bellows, the arrangement and type of pump used therein and, therefore, the V form of theinvention described above should be considered illustrative and not as limiting the scope of the following claims. f

I claim:

a pair of telescopically related cylindrical casings Joined at one end and otherwise spaced apart to provide a pressure chamber, an expansible metallic bellows interposed between said casings forming with the inner casing an accumulator chamber for receiving liquid under pressure, a pump mounted within said inner casing and having an inlet and a discharge outlet for high pressure liquid, and by-pass means connecting said outlet to said accumulator chamber to supply liquid to the latter to 'expand said bellows and accumulate a reserve supply of liquid under. pressure. 1

2. A hydraulic power supply unit, comprising an accumulator having an outer sealed casing, an inner hollow casing and an expansible metallic bellows interposed between said casings and dividing the space therebetween into an outer gas-receiving chamber and an inner liquidsure to a hydraulic system.- by-pass means for delivering liquid under pressure to saidliquidreceiving chamber, and means within said inner casing responsive to liquid prsure in said outlet for renderng said pump inoperative to supply liquid when the liquid pressure attains a predeterminedmaximum and for rendering said pump operative when the liquid pressure drops to a predetermined lower pressure.

3. A hydraulic power supply unit. comprising an outer cylindrical casing, a shorter hollow inner cylindrical casing telescoped withinsaid outer casing. `ioined thereto at one end and otherwise spaced therefrom to form a chamber between the ends of said casings and an annular space between the sides of said casings. an expansible metallic bellows disposed in said chamber and space and enclosing said inner casing, a pistontype pump mounted inside said inner casing and.

having a liquid inlet, a discharge outlet. a plurality of pistons for drawing liquid through said inlet casing enclosing and secured to said pump casing at one end and having a closure provided with a port at its other end, a substantially cylindrical outer casing enclodng said inner casing, sealed thereto at one end and otherwise spaced from and discharging it under pressure through said `forming a gas-receiving chamber between said outer casing and said partition and a liquidreceiving chamber between said partition and said inner casing, a pump mounted within said inner casing having an inlet and an outlet. disconnectible drive means for said pump, means connecting said outlet to said liquid-receiving chamber. and means responsive to liquid pressure in said outlet for connecting and disconnecting said drive means at predetermined minimum and maximum liquidpressures, respectively.-

5. A hydraulic power supply unit, comprising an accumulator having an cuter casing, an inner casing telescoped within said outer casing, an expansible partition between said casings and forming a gas-receiving chamber between said cuter casing and said partition and a liquidreceiving chamber between said partition and sad inner casing, a pump mounted within said inner casing having an inlet and an outlet, and means connecting said outlet to said liquidreceiving chamber.

6. A hydraulic power supply unit. comprising an accumulator having an outer casing, an inner casing telescoped within said outer casing, an expansible partition between saidvcasings and having a gas-receiving chamber between said outer casing and said. partition and a liquidreceiving chamber between said partition and said inner casing. a pump mounted within said inner casing having an inlet and anoutlet, disconnectible drive means for said pump, means connecting said outlet to said liquid-receiving chamand maximum 1 Number said inner easing, the opposite end of said outer casing being closed, a cup-shaped expansible metallic bellows interposed between said outer and inner casings. enclosing the latter and sealingsaid inner casing from said outer casing, and bypass means connecting said outlet passage to said port to allow liquid to iiow into and out of said bellows.

8. A hydraulic pressure supply unit. comprising a. piston-type pump having a casing. inlet and discharge passages in said casing, pumping elements mounted in said casing for drawing liquid through said inlet passage and discharging it through said discharge passage, a hollow, substantially cylindrical inner casing enclosing and secured to said pump casing at one end and having a closure provided with a portat its other end, asubstantially cylindrical outer casing enclosing said inner casing, sealed thereto at one end and otherwise spaced from said inner casing, the opposite end of said outer casing being closed, a cup-shaped expanslble metallic bellows interposed between said outer and inner casings, enclosing the latter and sealing said inner casing from said outer casing, means responsive to liquid pressure in said discharge passage for maintaining the pressure therein within .a predetermined pressure range, and by-pass means connecting said outlet passage to said' port to allow liquid to flow into and out oi said bellows.

Y BENJAMIN N. ASHTON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date 1,908,092 Whitted May 9, 1933 2,139,571 Avigdor Dec. 6, 1938 2,161,158 Gossler June 6, 1939 2,197,772 Rockwell Apr. 23, 1940 .2,267,656 Jeifrey Dec. 23, 1941 2,307,246 Szekely Jan. 5, 1943 2,365,994 Ashton Dec. 26, 1944 2,405,006 Y Ashton July 30, 1946 

